Fibre optic network design method

ABSTRACT

A system and method of designing a fiber optic network for a plurality of premises in a geographic area that has existing infrastructure is described. They include electronically receiving fiber optic network design inputs that include data indicative of a plurality of nodes in the fiber optic network and data indicative of arcs extending between said nodes in the fiber optic network based on allocated bandwidth for said premises in the geographic area, electronically receiving existing infrastructure design inputs comprising data indicative of said existing infrastructure that can be used as geographic locations for said nodes and said arcs in the fiber optic network, electronically generating design outputs by optimizing geographic locations of said nodes and said arcs in the fiber optic network using said fiber optic network design inputs and said existing infrastructure inputs, and electronically outputting the design outputs.

TECHNICAL FIELD

The present invention relates to a method of designing a fibre opticnetwork for a plurality of premises in a geographic area comprisingexisting infrastructure for utilities in the geographic area. Thisapplication is based on and claims the benefit of the filing date ofAustralian provisional patent application no. 2010903705 filed 18 Aug.2010, the content of which, as filed, is incorporated herein byreference in its entirety.

BACKGROUND

Optical fibre can be used as a medium for telecommunication andnetworking because it is flexible and can be bundled as cables. It isespecially advantageous for long-distance communications because lightpropagates through the fibre with little attenuation compared withelectrical cables. In recent times, vast fibre optic networks have beencommissioned to cope with the increasing growth in Internetcommunication and cable television.

In one existing example, fibre optic networks are designed manually witha view of ensuring that engineering and other physical requirements aremet. Not only is this manual design process often laborious and timeconsuming, but the resulting network design is often far from ideal byincluding more infrastructure than is absolutely necessary, whichultimately adds to network cost. In addition, manually modifying thedesigned network to reduce the amount of infrastructure, or in responseto changing requirements, is also a laborious and time consuming task.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, there is provided amethod of designing a fibre optic network for a plurality of premises ina geographic area that has existing infrastructure, the methodcomprising:

-   -   electronically receiving fibre optic network design inputs        comprising data indicative of a plurality of nodes in the fibre        optic network and data indicative of arcs extending between said        nodes in the fibre optic network based on allocated bandwidth        for said premises in the geographic area;    -   electronically receiving existing infrastructure design inputs        comprising data indicative of said existing infrastructure that        can be used as geographic locations for said nodes and said arcs        in the fibre optic network;    -   electronically generating design outputs by optimising        geographic locations of said nodes and said arcs in the fibre        optic network using said fibre optic network design inputs and        said existing infrastructure inputs whereby said design outputs        comprise the optimised geographic locations of said nodes and        said arcs in the fibre optic network relative to said existing        infrastructure; and    -   electronically outputting the design outputs.

It will be appreciated by those skilled in the art that the term “arc”is used herein in the manner commonly employed in this art, that is, todescribe connections, for example, between nodes or between nodes andpremises, and which may not describe geometrical arcs.

Typically, optimising will involve minimizing cost, subject to thedesign inputs, but may involve minimizing damage to the environment ormaximizing average user bandwidth to the premises.

It will be appreciated by those persons skilled in the art that the dataindicative of the plurality of nodes includes at least a proposedgeographic location of the nodes for the fibre optic network, and anumber of the nodes for the network.

In an embodiment, the existing infrastructure comprises infrastructurefor utilities in the geographic area (e.g. a suburb), such as a powernetwork and/or a telecommunications network. Thus, for example, thedesign of the fibre optic network comprises a layout of optimisedgeographic locations for nodes and arcs of the fibre optic networkmaximising the use of existing infrastructure, such as power polesand/or telecommunications pits and ducts, to minimise costs associatedwith construction of the fibre optic network. Optimisation can thus beperformed with respect to one or more existing infrastructure networks,each network forming different layers in the geographic area for designof the fibre optic network.

In an embodiment, the method facilitates speedy design of the network,requiring less infrastructure to be constructed by reusing existinginfrastructure where optimal, by virtue of performing the fibre opticnetwork design method with a computational device (e.g. a server). Thatis, the method minimises the monetary construction cost of the designednetwork, and by keeping the cost to a minimum unnecessary infrastructureis advantageously not included in the design.

In an example, in use, the method is more time effective than knowndesign methods and, for example, each performance of the fibre opticnetwork design method takes minutes, compared with manual methods whichcan take weeks.

In an additional embodiment, the method facilitates speedy redesign byfacilitating the altering of the design inputs and re-performing thefibre optic network design method using the altered inputs.

In an embodiment, the method further comprises electronically receivingsaid fibre optic network design inputs further comprising dataindicative of a plurality of arcs extending between said nodes and eachof said premises. In the embodiment, the arcs comprise or correspond toat least one fibre optic cable. It will be appreciated by those personsskilled in the art that each premise comprises a demand for one or moreindividual fibres of the fibre optic cable based on their allocatedbandwidth.

In an embodiment, the nodes comprise or correspond to Fibre DistributionHubs (FDHs) or fibre optic cable splice locations. It will beappreciated by those persons skilled in the art that each FDH isallocated a capacity given by the amount of individual fibres of thefibre optic cables that can be handled thereat. Thus, each FDH isallocated a number of premises to supply optic fibres to.

In an embodiment, the method further comprises estimating said pluralityof nodes and said arcs in the fibre optic network based on saidallocated bandwidth for said premises in the geographic area. Forexample, in use, a network designer will estimate the location of thenodes and arcs of the network based on the allocated bandwidth forpremises and their location in the geographic area, and this estimateforms the fibre optic network design input data. The estimated locationis then optimised by performing optimisation on these inputs withrespect to inputs indicative of the existing infrastructure to reuseexisting infrastructure to minimise construction costs of the network.

In an embodiment, the existing infrastructure comprises a power networkand said optimised geographic locations of said nodes comprises aplurality of power poles of the power network so that said at least onefibre optic cable can be hung therebetween, thereby forming theoptimised geographic locations of said arcs. In another embodiment, theexisting infrastructure further comprises a duct network having aplurality of pits and a plurality of existing ducts therein and saidoptimised geographic locations of said nodes further comprises saidplurality of pits of the duct network so that said fibre optic cablescan be laid in said existing ducts therebetween, thereby further formingthe optimised geographic locations of said arcs. That is, the FDHs andcable splice locations can be located at the power poles or pits so thatarcs of fibre optic cables can be hung therebetween or laid therebetweento minimise construction costs associated with digging trenches for newducts.

In an embodiment, the optimised geographic locations of said arcsfurther comprises new ducts, not of the duct network, so that said fibreoptic cables can be laid therein, between said nodes and between saidnodes and said premises, where said existing infrastructure cannot beused for the fibre optic network. It will be appreciated by thosepersons skilled in the art that some new ducts are required whereexisting infrastructure cannot be conveniently used or does not exist.

In an embodiment, the method further comprises electronically receivingsaid fibre optic network design inputs further comprising dataindicative of costs of said arcs that are to be laid in said new ducts,said existing ducts, and that are to be hung between said power poles.For example, the cost of constructing a new duct is $50/meter, the costof hanging fibre optic cables between power poles is $2/meter, and thecost of laying fibre optic cables in existing ducts is $5/meter.

In an embodiment, the method further comprises electronically receivingsaid fibre optic network design inputs further comprising dataindicative of costs of said arcs comprising costs associated with anumber of said at least one fibre optic cable and length thereof foreach of said arcs in the fibre optic network. For example, the cost offibre optic cable, having a core of eight fibres, is $3/meter, and$5/meter for cable with a core of sixteen fibres.

In an embodiment, the method further comprises electronically receivingsaid fibre optic network design inputs further comprising dataindicative of costs of each of said FDHs and said fibre splice locationsfor each of said nodes in the fibre optic network. For example, the costof an FDH with the capability of handling 1000 optical fibres is $50 andthe cost of splicing an eight core optical fibre at a splicing locationis $2.

In an embodiment, the method further comprises displaying the design ofthe fibre optic network with respect to a map of the geographic areausing the design outputs. The design outputs may be stored in a file andthe map may be generated by inputting the file into an appropriate geospatial application.

In an embodiment, the method further comprises performing optimisationwith respect to said fibre optic network design inputs and said existinginfrastructure inputs using an optimisation model. In the embodiment,the optimisation model comprises a tree optimisation model whereby eachtree is centred at one of said nodes and comprises one or more of saidarcs connected thereto. That is, the fibre optic network design includesone or more node arc trees each with cable branches extending from thenodes, where each node relates to a Fibre Distribution Hub (FDH) or acable splice location and each tree includes a single FDH. It will beappreciated by those persons skilled in the art, however, that otheroptimisation models can be used such as a spanning tree model.

Also, the above optimisation model further comprises a linearoptimisation function subject to linear and/or integer constraints. Forexample, the optimisation function may combine costs relating to FibreDistribution Hubs (FDHs), fibre splices, trenching costs, aerialinstallation costs and cable costs. The constraints may relate to anyone or more of: traffic flow requirements at a node, conditionalbranching of the network, traffic flow requirements of a cable or arc,distance between network components, the available candidate networks(poles, new trenches or existing capacitated trenches) within which thefibre optic network is being installed, and the demand by premise andpermitted geographic locations for equipment.

In an embodiment, the design inputs include user defined inputs for thenetwork design, such as those defined by the network designer estimatingthe network, and generic network inputs for any network design. Forexample, the user defined inputs include any one or more of an inputnode domain set relating to allowed geographic location of nodes in thenetwork design, an input arc domain set relating to allowed geographiclocation of arcs in the network design, an input cable type domain setrelating to allowed types of cable to be used in the network design, andan optimisation parameter set for the optimisation model. Also, thegeneric network inputs include information relating to minimum andmaximum number of Fibre Distribution Hubs (FDH) in the network, thecapacity (number of fibres connecting to) of each FDH, and networkcomponent costs.

According to another aspect of the present invention, there is provideda system for designing a fibre optic network for a plurality of premisesin a geographic area that has existing infrastructure, the systemcomprising:

-   -   an input module arranged to receive fibre optic network design        inputs comprising data indicative of a plurality of nodes in the        fibre optic network and data indicative of arcs extending        between said nodes in the fibre optic network based on allocated        bandwidth for said premises in the geographic area;    -   the input module further arranged to receive existing        infrastructure design inputs comprising data indicative of said        existing infrastructure that can be used as geographic locations        for said nodes and said arcs in the fibre optic network;    -   an optimising module arranged to generate design outputs by        optimising geographic locations of said nodes and said arcs in        the fibre optic network using said fibre optic network design        inputs and said existing infrastructure inputs, whereby said        design outputs comprise the optimised geographic locations of        said nodes and said arcs in the fibre optic network relative to        said existing infrastructure; and    -   an output module arranged to output the design outputs.

In an embodiment, the system further comprises a display module arrangedto display the design of the fibre optic network with respect to a mapof the geographic area using the design outputs.

According to another aspect of the present invention, there is providedcomputer program code usable to configure a server to implement a methodof designing a fibre optic network for a plurality of premises in ageographic area that has existing infrastructure, the server beingconfigured to:

-   -   receive fibre optic network design inputs comprising data        indicative of a plurality of nodes in the fibre optic network        and data indicative of arcs extending between said nodes in the        fibre optic network based on allocated bandwidth for said        premises in the geographic area;    -   receive existing infrastructure design inputs comprising data        indicative of said existing infrastructure that can be used as        geographic locations for said nodes and said arcs in the fibre        optic network;    -   generate design outputs by optimising geographic locations of        said nodes and said arcs in the fibre optic network using said        fibre optic network design inputs and said existing        infrastructure inputs, whereby said design outputs comprising        the optimised geographic locations of said nodes and said arcs        in the fibre optic network relative to said existing        infrastructure; and    -   output the design outputs.

According to another aspect of the present invention, there is providedcomputer program code which when executed implements the above describedmethod.

According to another aspect of the present invention, there is provideda computer readable medium comprising the above program code. In anarrangement, the medium, such as a magnetic or optical disk or solidstate memory, contains computer readable instructions for execution by aprocessor to thereby perform the preceding method.

According to another aspect of the present invention, there is provideda data signal comprising the above described program code.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention can be more clearly ascertained, embodimentswill now be described, by way of example, with reference to theaccompanying drawings, in which:

FIG. 1 is a schematic diagram of an embodiment of the present invention;

FIG. 2 is a flow diagram of an embodiment of the present invention;

FIG. 3 is a schematic diagram of a computational device according to anembodiment of the present invention;

FIG. 4 shows, by way of example, a user interface of a network designspreadsheet for a fibre optic network design software product executedon the computational device of FIG. 3;

FIG. 5 shows a map of a fibre optic network design produced by anembodiment of the invention, the map being displayed using designoutputs produced using the network design spreadsheet of FIG. 4; and

FIG. 6 is a flow diagram of a fibre optic network design method inaccordance with an embodiment of the present invention.

DETAILED DESCRIPTION

According to an embodiment of the present invention, there is provided asystem 200, as shown in FIG. 1, for designing a fibre optic network fora plurality of premises in a geographic area, such as a suburb,comprising existing infrastructure for utilities in the suburb, such asinfrastructure for a power network. The system 200 comprising an inputmodule 202 arranged to receive fibre optic network design inputscomprising data indicative of a plurality of nodes in the fibre opticnetwork and data indicative of a plurality of arcs extending between thenodes in the fibre optic network based on allocated bandwidth forpremises in the suburb. The input module 202 is also arranged to receiveexisting infrastructure design inputs comprising data indicative of theexisting infrastructure that can be used as geographic locations for thenodes and arcs in the fibre optic network. The system 200 furtherincludes an optimising module 204 arranged to perform optimisation withrespect to the fibre optic network design inputs and the existinginfrastructure inputs to optimise the geographic locations of the nodesand the arcs and to generate design outputs comprising the optimisedgeographic locations of the nodes and arcs in the fibre optic networkrelative to the existing infrastructure to, for example, minimise costsassociated with construction of the fibre optic network. Also, thesystem 200 includes an output module 206 arranged to output the designoutputs for design of the fibre optic network. In this way, the nodescan be located at locations of existing infrastructure, such as powerpoles, and arcs of fibre optic cables hung therebetween.

In the embodiment shown in FIG. 1, the input 202, optimising 204 andoutput modules 206 reside on a server 208 accessible by an electronicdevice 212 over a network 210, such as the Internet. The server 208comprises a processor 214 arranged to implement the input 202,optimising 204 and output modules 206 and a memory 216 comprising adatabase 218 to store instructions to perform optimisation using thefibre optic network design inputs and the existing infrastructure inputsto generate the design outputs for output over the network 210 to auser, such as a network designer, of the electronic device 212 (e.g. acomputer).

Thus, in use, the network designer estimates the location of the nodesand arcs of the fibre optic network based on the allocated bandwidth forthe premises and their location in the geographic area, and theelectronic device 212, using a suitable module, generates the fibreoptic network design input data based on the estimate, and communicatesthe input data over the network 210 to the server 208. It is alsoenvisaged that the input 202, optimising 204 and output modules 206 canreside on a stand-alone computing device arranged to facilitate input ofthe fibre optic network design inputs and output of the design outputsfor design of the fibre optic network. In any case, the input module 202receives the estimates along with data indicative of the existinginfrastructure so that the optimising module 204 can performoptimisation on these inputs to generate a network design reusingexisting infrastructure to minimise construction costs of the network asdescribed above.

Also as described, the arcs extend between the nodes and each of thepremises so that each premise receives at least one optical fibre andeach node of the network comprises a Fibre Distribution Hub (FDH) or afibre optic cable splice location. In the example given below, theexisting infrastructure comprises only one utility network: a powernetwork. However, as described above, the system 200 can be applied tomore than one utility network (e.g. a power network andtelecommunications network) to generate a multi-layered network designreusing different types of existing infrastructure.

In the example, the optimising module 204 performs optimisation on theinputted estimated node and arc location with respect to the location ofpower poles and underground ducts of the power network to minimise theneed to dig new trenches for new ducts for the optic fibre cables. Inthis way, the nodes of the network can be located at the power poles orunderground pits of the power network so that the arcs of fibre opticcable can be hung or laid therebetween. Optimisation is performed by theoptimising module 204 on the inputs using an optimisation model in theform of a tree optimisation model, whereby each tree has a FDH centredat one of the nodes and comprises one or more of said arcs connectedthereto. This model can be expressed as a linear optimisation functionsubject to a number of linear and integer constraints, which is asfollows:

${{minimise}\mspace{20mu} C^{H}{\sum\limits_{p \in H}\; z_{p}}} + {C^{S}{\sum\limits_{p \in H}\; w_{p}}} + {\sum\limits_{{a \in A},{t \in T}}\;{C_{at}^{A}y_{at}}}$

Subject to the constraints:

$\begin{matrix}{{{M^{H}z_{p}} + {\sum\limits_{a,{T_{a} = p}}\; x_{a}}} \geq {D_{p} + {\sum\limits_{a,{F_{a} = p}}\;{x_{a}\mspace{34mu}{\forall p}}}}} & (1) \\{{{z_{p} + {\sum\limits_{t,a,{T_{a} = p}}\; y_{at}}} = {1\mspace{31mu}{\forall p}}},{D_{p} > 0}} & \left( {2\; a} \right) \\{{{\sum\limits_{t,a,{T_{a} = p}}\; y_{at}} \leq {1\mspace{31mu}{\forall p}}},{D_{p} = 0}} & \left( {2\; b} \right) \\{{{{z_{p}d_{p}} + {w_{p}\left( {d_{p} - 1} \right)} + {\sum\limits_{a,{T_{a} = p}}\; y_{at}}} \geq {\sum\limits_{a,{F_{a} = p}}\;{y_{at}\mspace{31mu}{\forall p}}}},t} & (3) \\{x_{a} \leq {\sum\limits_{t}\;{M_{t}y_{at}\mspace{31mu}{\forall a}}}} & (4)\end{matrix}$

The optimisation model assumes the following data:

-   -   A set of N^(P) power poles P indexed by p (where the term pole        and power pole are used interchangeably).    -   Each pole has a demand D_(p)—the number of fibres that are        needed at this pole    -   A set of N^(A) possible arcs A indexed by a, each going from        pole F_(a) to pole T_(a). Each span will correspond to two arcs.        The length of arc a is given by l_(a)    -   The degree of each pole, d_(p)—the number that start at (and end        at) pole p    -   The set H of poles which are potential FDH's or Splice        locations. A splice location is a location where one cable can        be joined to two other cables, usually a larger one into two        smaller ones. Note all poles may be allowed to locate an FDH or        a splice.    -   The fixed cost of an FDH—C^(H).    -   A set of N^(T) cable types T indexed by t. Each cable type has a        maximum fibre capacity M_(t). Each arc a has a known cost for        being connected by cable type t=C_(at) ^(A). This is calculated        from the type of arc, its length and the type of cable.    -   M^(H) is the maximum fibre capacity for an FDH.

The above variables are defined as follows:

-   -   z_(p)∈{0,1}, which is 1 if pole p is used as an FDH. By        definition z_(p)=0 if p∉H.    -   w_(p)∈{0,1}, which is 1 if pole p is used as a splice location.        By definition w_(p)=0 if p∈H.    -   y_(at)∈{0,1}, which is 1 if arc a has a cable of type t        installed.    -   x_(a) which is the “fibre flow” on arc a. That is, the number of        free fibres that will be available at the end pole.

Constraint (1) ensures that the “fibre flow” into a pole is at least aslarge as the demand at the pole plus the fibre flow out of the pole. Foran FDH, “inwards fibre flow” will be the capacity of the FDH(M^(H)z_(p)).

Constraint (2a) ensures that a pole with demand is either an FDH or ithas exactly one cable connecting in to it. If a pole has no demand, itmust have at most one cable connecting in to it (2b). These constraints,together with the preservation of cable types imposed by constraint (3),ensure that there is no branching in the distribution cable network,except at an FDH or a splice.

Constraint (3) ensures that for each pole the inflow of a particularcable type is at least as large as the outflow of that cable type,unless the pole is an FDH or a splice.

Constraint (4) ensures that the “fibre flow” on an arc is less than themaximum for the installed cable.

Thus, the optimisation function can be seen as minimising the combinedconstruction cost of installed FDH's, splices and the cost of installingcables between nodes and between nodes and premises by utilisingexisting infrastructure where possible rather than, say, digging newtrenches for the arcs of the network. The design outputs from theoptimisation function can then applied to a map of the suburb forconstruction of the network.

Referring now to FIG. 3, there is depicted a block diagram of aconventional computational device 3 of a type suitable for performingthe method according to a preferred embodiment of the present invention.That is, FIG. 3 depicts the embodiment where the input 202, processing204 and output 204 modules of FIG. 1 reside on the computational device3.

The computational device 3 of FIG. 3 includes a computer case 2 whichhouses a processor 8 (or one or more processors) that accesses RAM 12,ROM 14 and various secondary data storage devices 16 such as hard diskdrives. The processor 8 executes a software product 18 stored in datastorage 16 that contains instructions for performing the above describedfibre optic network design method. In this embodiment, the input 202,processing 204 and output 204 modules of FIG. 1 are implemented by thesoftware product 18.

The fibre optic network design software product 18 for designing fibreoptic networks can be executed using a personal computer (PC), which isa form of the computational device 3, and the software product 18 canupdate outputs when desired network design inputs are varied by anetwork designer. The fibre optic network design software product 18 isalso provided on an optical or magnetically readable medium, such as aCD-ROM 29, though it might also be provided in a ROM or other electroniccircuit as firmware or provided over a distributed computer network suchas the Internet. The software product 18 also includes instructions forthe computational device 3 to implement the fibre optic network designmethod.

By means of conventional interfacing circuitry located on a main board10 within the case 2, the processor 8 receives commands from inputdevices such as a keyboard 4 and mouse 20. The processor 8 also controlsand communicates with a number of peripheral devices including a scanner24, for converting documents into electronic file format, a printer 26for converting files, spreadsheets and maps into paper hardcopy 28, andan optical disk writer 22 for permanently writing files, spreadsheetsand maps to a removable optical disk 29. The processor 8 alsocommunicates with remote computers via a network support module, such asa LAN switch or Internet gateway.

In use, the computer system 3, executing the software product 18,receives design inputs from the fibre optic network designer 30, forexample using the keyboard 4 and the mouse 20, relating to the networkdesign and the existing infrastructure. That is, the designer 30 entersthe inputs into the software product 18, which is displayed on thedisplay 6 of the computational device 3. The computational device 3 thenperforms calculations for the optimisation model based on the inputsfrom the designer 30 and produces design outputs relating to the networkdesign, which are displayed on the display 6 of the computational device3 and stored in a file on the data storage device 16.

FIG. 4 shows, by way of example, a user interface 50 for the softwareproduct 18, generated by the software product 18, which was executed onthe computational device 3. The user interface 50 includes designerdefined inputs 52 for a given network design and generic network inputs54 (or parameters) for any network design, including the fibre opticnetwork design inputs and the existing infrastructure design inputs, anddesign outputs 56 as indicated below.

The designer defined inputs 52 include a node domain set 58 relating tofeasible geographic location of nodes. In practice, these may be a setof usable power poles of the existing power infrastructure in thegeography being modelled, or they may be a set of nodes representingstreet junction points or intersections. The inputs 52 also include thenumber of fibres that have to be delivered to each node in the networkdesign (e.g. demand) and an arc domain set 60 relating to feasiblegeographic location of arcs, which can be used to connect nodes withcables of a specific type. In practice, the arc domain set 60 can eitherbe defined by the set of power poles that are connected by existingelectrical infrastructure, or the pre existing duct network which may beavailable for use, or they can represent the connection between nodesrepresenting street junctions or intersections to host new trenchednetworks, or a combination thereof. The inputs 52 further include acable type domain set 62 relating to feasible types of cable to be usedin the network design, and an optimisation model parameter set 64 forthe optimisation model.

The generic network inputs 54 include information relating to theminimum and maximum number of FDHs 70, the fibre capacity 72 of each FDH(the maximum number of fibres connect to a FDH), the maximum distancefrom an FDH to a node, the allowable consumable capacity of fibres inthe allowable cable set, the entry point of the distribution cable intothe area being planned 87, whether splicing is allowed 88, the number offibres per tube 91 in accordance with the reference architecture,whether or not the solution must include only trenched cable, or acombination of both trenched and aerial cable and network componentcosts 76. The network component costs 76 include the fixed cost 78 ofeach FDH, splice enclosure costs 80, the fixed cost of an individualfibre splices and splice enclosure pits 82, aerial cable installationcost (per meter) 84, trenching costs (per meter), hauling fibre throughtrenched ducts (cost per meter) 86 and cable costs (per meter).

The base data required is the location of nodes, the fibre demand foreach node, and a determination of whether the node can act as an FDH orcable splice location. These data sets also have a number of spans orarcs—potential connection between nodes. Spans can be thought of asundirected potential arcs that may or may not be used in the outputdesign. Each potential arc includes a determination of whether or not itcan be used to string aerial cable only, run trenched cable only, orstring both aerial and run trenched cable.

Design outputs 56 include an output node set 88 relating to optimisedgeographic location of FDHs and cable splice nodes in the network designand an output arc set 90 relating to optimised use of arcs in thenetwork design, including whether or not each arc is used to stringaerial cable only, run new trenched cable only, utilize pre existingduct capacity only, or both string aerial and run trenched cable (new orpre existing). Also, the design outputs include the type of cable usedand the utilized capacity in each specific cable.

The cost optimisation model thus determines a suitable fibre opticnetwork design 20 with a minimum number of components and thereforeminimum cost. Referring to FIG. 5, the fibre optic network design 100includes one or more disconnected trees 101 each with cable branchesextending from nodes located at street intersections. The fibre opticnetwork design 100 is obtained using a display module (not shown)arranged to display the design of the fibre optic network with respectto a map of the geographic area using the design outputs.

The tree 101 shown in FIG. 5 includes one FDH 102, which is the fibreconnection node for cables 104 in the network 100. Also, splices 106join two cables together to form a continuous optical waveguide. Asdescribed, the tree can only branch at nodes which are either the FDH102 or splices 106 and the cable connection between nodes is achieved bystringing aerial cable, running trenched cable, or both stringing aerialand running trenched cable along an arc. In practice, there is a costincurred for every arc and node in the network design depending on howthe arc is used to connect the nodes at either end of the arc with cable100. It can be seen that not all streets 105 have been designed to havecable deployed and arcs to individual premises are not shown.

In use, the fibre optic network design 100 shown in FIG. 5 is obtainedusing an embodiment of the method 150 of designing an optical fibrenetwork shown in FIG. 6. Here it can be seen that the software product18 described above: receives 152 design inputs relating to fibre opticnetwork design including sets of feasible node and arc locations basedon, for example, bandwidth allocation for premises in the suburb andexisting infrastructure information, performs optimisation 154 byapplying the above described optimisation model with respect to theinputs, and displays 156 a map of the fibre optic network design 100using the optimised outputs. The designer can then repeat 158 thedesigning process for another fibre optic network design 100.

Referring back to FIG. 2, there is shown a summary of a method 220 ofdesigning a fibre optic network for a plurality of premises in ageographic area. The method 220 comprises receiving 222 fibre opticnetwork design inputs comprising data indicative of a plurality of nodesin the fibre optic network and data indicative of a plurality of arcsextending between the nodes in the fibre optic network based onallocated bandwidth for the premises in the geographic area, receiving224 existing infrastructure design inputs comprising data indicative ofthe existing infrastructure that can be used as geographic locations forthe nodes and the arcs in the fibre optic network, generating 226 designoutputs by optimising the geographic location and the nodes and the arcsusing the fibre optic network design inputs and the existinginfrastructure inputs, whereby the design outputs comprise the optimisedgeographic locations of the nodes and the arcs in the fibre opticnetwork relative to the existing infrastructure to, for example,minimise costs associated with construction of the fibre optic network,and outputting 228 the design outputs for design of the fibre opticnetwork.

Further aspects of the method 220 will be apparent from the abovedescription of the system 200. Persons skilled in the art willappreciate that the method could be embodied in program code, executedby a processor, which could be supplied in a number of ways, for exampleon a computer readable medium, such as a disc or a memory, or as a datasignal, such as by transmitting it from a server. Persons skilled in theart will also appreciate that program code provides a series ofinstructions to implement the method.

It will also be understood to those persons skilled in the art of theinvention that many modifications may be made without departing from thespirit and scope of the invention.

It will also be understood that the reference to any prior art in thisspecification is not, and should not be taken as an acknowledgement orany form of suggestion that the prior art forms part of the commongeneral knowledge in any country.

In the claims which follow and in the preceding description of theinvention, except where the context requires otherwise due to expresslanguage or necessary implication, the word “comprise” or variationssuch as “comprises” or “comprising” is used in an inclusive sense, i.e.to specify the presence of the stated features but not to preclude thepresence or addition of further features in various embodiments of theinvention.

The invention claimed is:
 1. A method of designing a fibre optic networkfor a plurality of premises in a geographic area that has existinginfrastructure, the method comprising: electronically receiving fibreoptic network design inputs comprising data indicative of a plurality ofnodes in the fibre optic network and data indicative of arcs extendingbetween said nodes in the fibre optic network based on allocatedbandwidth for said premises in the geographic area; electronicallyreceiving existing infrastructure design inputs comprising dataindicative of said existing infrastructure that can be used asgeographic locations for said nodes and said arcs in the fibre opticnetwork; electronically generating design outputs by optimisinggeographic locations of said nodes and said arcs in the fibre opticnetwork using said fibre optic network design inputs and said existinginfrastructure inputs and using an optimisation model comprising alinear optimisation function subject to linear and integer constraints,wherein said design outputs comprise the optimised geographic locationsof said nodes and said arcs in the fibre optic network relative to saidexisting infrastructure; and electronically outputting the designoutputs, wherein said existing infrastructure comprises a power networkand said optimised geographic locations of said nodes comprises aplurality of power poles of the power network so that at least one fibreoptic cable can be hung therebetween.
 2. A method as claimed in claim 1,wherein said fibre optic network design inputs further comprise dataindicative of a plurality of arcs extending between said nodes and eachof said premises.
 3. A method as claimed in claim 2, wherein: i) each ofsaid arcs comprises at least one fibre optic cable; ii) said nodescomprise Fibre Distribution Hubs (FDHs) or fibre optic cable splicelocations; or iii) each of said arcs comprises at least one fibre opticcable and said nodes comprise Fibre Distribution Hubs (FDHs) or fibreoptic cable splice locations.
 4. A method as claimed in claim 1, whereinsaid existing infrastructure comprises a duct network having a pluralityof pits and a plurality of existing ducts therein, said optimisedgeographic locations of said nodes further comprise said plurality ofpits of the duct network so that fibre optic cables can be laid in saidexisting ducts therebetween, and said optimised geographic locations ofsaid arcs further comprise new ducts, not of the duct network, so thatsaid fibre optic cables can be laid therein where said existinginfrastructure cannot be used for the fibre optic network.
 5. A methodas claimed in claim 1, wherein said fibre optic network design inputsfurther comprise data indicative of costs.
 6. A method as claimed inclaim 1, further comprising: i) displaying the design of the fibre opticnetwork with respect to a map of the geographic area using the designoutputs; and/or ii) estimating said plurality of nodes and said arcs inthe fibre optic network based on said allocated bandwidth for saidpremises in the geographic area.
 7. A method as claimed in claim 1,wherein said optimisation model comprises a tree optimisation modelwhereby each tree is centred at one of said nodes and comprises one ormore of said arcs connected thereto.
 8. A method as claimed in claim 1,wherein said existing infrastructure comprises a duct network having aplurality of pits and a plurality of existing ducts therein, whereinsaid optimised geographic locations of said nodes further comprise saidplurality of pits of the duct network so that fibre optic cables can belaid in said existing ducts therebetween.
 9. A computing system fordesigning a fibre optic network for a plurality of premises in ageographic area that has existing infrastructure, the system comprising:a processor; an input arranged by the processor to receive fibre opticnetwork design inputs comprising data indicative of a plurality of nodesin the fibre optic network and data indicative of arcs extending betweensaid nodes in the fibre optic network based on allocated bandwidth forsaid premises in the geographic area; the input further arranged by theprocessor to receive existing infrastructure design inputs comprisingdata indicative of said existing infrastructure that can be used asgeographic locations for said nodes and said arcs in the fibre opticnetwork; an optimising module executable by the processor to generatedesign outputs by optimising geographic locations of said nodes and saidarcs in the fibre optic network using said fibre optic network designinputs and said existing infrastructure inputs and using an optimisationmodel comprising a linear optimisation function subject to linear andinteger constraints, wherein said design outputs comprise the optimisedgeographic locations of said nodes and said arcs in the fibre opticnetwork relative to said existing infrastructure; and an output arrangedby the processor to output the design outputs, wherein said existinginfrastructure comprises a power network and said optimised geographiclocations of said nodes comprises a plurality of power poles of thepower network so that at least one fibre optic cable can be hungtherebetween.
 10. A system as claimed in claim 9, wherein said fibreoptic network design inputs further comprise data indicative of aplurality of arcs extending between said nodes and each of saidpremises.
 11. A system as claimed in claim 9, wherein: i) each of saidarcs comprise at least one fibre optic cable; ii) said nodes compriseFibre Distribution Hubs (FDHs) or fibre optic cable splice locations; oriii) each of said arcs comprise at least one fibre optic cable and saidnodes comprise Fibre Distribution Hubs (FDHs) or fibre optic cablesplice locations.
 12. A system as claimed in claim 9, wherein saidexisting infrastructure comprises a duct network having a plurality ofpits and a plurality of existing ducts therein, said optimisedgeographic locations of said nodes further comprises said plurality ofpits of the duct network so that at least one fibre optic cable can belaid in said existing ducts therebetween, thereby further forming theoptimised geographic locations of said arcs, said optimised geographiclocations of said arcs further comprise new ducts, not of the ductnetwork, so that said fibre optic cables can be laid therein where saidexisting infrastructure cannot be used for the fibre optic network. 13.A system as claimed in claim 9, wherein said fibre optic network designinputs comprise data indicative of costs.
 14. A system as claimed inclaim 9, wherein: i) said system further comprises a display modulearranged to display the design of the fibre optic network with respectto a map of the geographic area using the design outputs; and/or ii)said plurality of nodes and said arcs in the fibre optic network isestimated based on said allocated bandwidth for said premises in thegeographic area.
 15. A system as claimed in claim 9, wherein saidoptimisation model comprises a tree optimisation model whereby each treeis centred at one of said nodes and comprises one or more of said arcsconnected thereto.
 16. A system as claimed in claim 9, wherein saidexisting infrastructure comprises a duct network having a plurality ofpits and a plurality of existing ducts therein, wherein said optimisedgeographic locations of said nodes further comprise said plurality ofpits of the duct network so that at least one fibre optic cable can belaid in said existing ducts therebetween, thereby further forming theoptimised geographic locations of said arcs.
 17. A non-transitorycomputer readable storage medium on which is encoded computer programcode configured to control a server to implement a method of designing afibre optic network for a plurality of premises in a geographic areathat has existing infrastructure, the computer program code beingconfigured to control the server to: receive fibre optic network designinputs comprising data indicative of a plurality of nodes in the fibreoptic network and data indicative of arcs extending between said nodesin the fibre optic network based on allocated bandwidth for saidpremises in the geographic area; receive existing infrastructure designinputs comprising data indicative of said existing infrastructure thatcan be used as geographic locations for said nodes and said arcs in thefibre optic network; generate design outputs by optimising geographiclocations of said nodes and said arcs in the fibre optic network usingsaid fibre optic network design inputs and said existing infrastructureinputs and using an optimisation model comprising a linear optimisationfunction subject to linear and integer constraints, wherein said designoutputs comprise the optimised geographic locations of said nodes andsaid arcs in the fibre optic network relative to said existinginfrastructure; and output the design outputs, wherein said existinginfrastructure comprises a power network and said optimised geographiclocations of said nodes comprises a plurality of power poles of thepower network so that at least one fibre optic cable can be hungtherebetween.
 18. A non-transitory computer readable storage medium onwhich is encoded computer program code which when executed implementsthe method of claim
 1. 19. A non-transitory computer readable storagemedium comprising the computer program code of claim 18 or designoutputs generated by execution of computer program code of claim 18.